86 Proceedings of the Royal Society of Victoria. 



which is also the most ventral part of the nasal furrow (v.n.f.). 

 The duct then passes outwards almost horizontally to open into 

 the nasal furrow. At this plane, in transverse sections, is also 

 seen the external aperture of the naso-palatine, or Stenson's duct 

 (Fig. 3, n./>.if.), into the mouth. This duct, which is .40 mm. 

 long, runs inwards, upwards, and backwards, piercing between 

 the premaxillae and palatine processes to its origin from the 

 ventral edge of the nasal furrow, some distance behind the open- 

 ing of Jacobson's duct into it (Fig. 4, n.p.d.). There is, therefore, 

 no direct communication between the cavity of the Organ and 

 Stenson's duct, except through the cavity of the nasal furrow ; 

 this is confirmed by the difference in structure between the wall 

 of Jacobson's duct and of Stenson's duct, and the intervening 

 nasal furrow. 



This condition may be compared with that described by Broom 

 as an exception among Marsupials in Aepyprymnus^ by Klein in 

 the Guinea-pig^ and Rabbit,* by Harvey in the Rat and Hedgehog,* 

 and by Broom in Dasypus.* It may also be contrasted with that 

 in Ornithorhynchus" and Dog,'' and the usual Marsupial and 

 higher Mammalian types, as described by Jacobson, Gratiolet, 

 Balogh, Fleischer, and Broom, in which Jacobson's Organ opens 

 into Stenson's duct, otherwise remaining closed, e.g.^ in Macro- 

 pus*, Phascologale', Dasyurus^", Didelphys", Perameles^'*, and 

 Phascolomys." The openings of Stenson's ducts into the mouth 

 cavity are separated by a well-marked papilla, the centre of 

 which becomes somewhat hollowed out (Fig. 3). This, as stated 

 above, is supported, anteriorly at least, by a fibrous continuation 

 from the prenasal cartilage {f.p.c). The similarity of the general 

 relations of the parts seen in such a section of Aepyprymnus as 



1 Proc. Linn. Soc. N.S.W., vol. xi., n.s., 1896, p. 610. 

 •2 Q.J.M.S., vol. xxi., p. 219. 



3 Loc. cit., p. 555-6. 



4 Q.J.M.S., vol. xxii., p. 50. 



5 Trana. Roy. Soc. Edin., vol. xxxix., p. 242. 



6 Proc. Zool. Soc. Lond., 1891, p. 578. 



7 Q.J.M.S., vol. xxii., p. 301-2. 



8 Jour. Anat. and Phys., vol. xxvi., p. 372. 



9 Proc. Linn. Soc. N.S.VV., vol. xi., n.s., 1896, p. 593. 



10 Loe. cit., p. 594. 



11 Loc. cit., p. 597. 



12 Loc. eit., p. 600. 



13 Loc. cit., p. 613. 



